^And also too low to cause any sort of effect after the initial honeymoon period (after the first few experiences), which is why I posted that. It's like an opioid naive user saying, "what if I were to dose 2.5mg hydrocodone once a month"? Eventually that 2.5mg becomes 5mg, then settles around 10mg at that dosage frequency.
I feel like the OP will eventually end up settling at 10mg Adderall per dose at that kind of dosage frequency, which is still a very low, responsible dosage. You're going about this the right way, OP. Always use the lowest dose possible, you can always take more the next time if it doesn't work.
On the other hand, the OP is very light. I weigh 82.5 kilos, so 5mg sounds about right, actually.